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PIPE(8) PIPE(8)
<b>NAME</b>
pipe - Postfix delivery to external command
<b>SYNOPSIS</b>
<b>pipe</b> [generic Postfix daemon options] command_attributes...
<b>DESCRIPTION</b>
The <a href="pipe.8.html"><b>pipe</b>(8)</a> daemon processes requests from the Postfix queue manager to
deliver messages to external commands. This program expects to be run
from the <a href="master.8.html"><b>master</b>(8)</a> process manager.
Message attributes such as sender address, recipient address and next-
hop host name can be specified as command-line macros that are expanded
before the external command is executed.
The <a href="pipe.8.html"><b>pipe</b>(8)</a> daemon updates queue files and marks recipients as fin-
ished, or it informs the queue manager that delivery should be tried
again at a later time. Delivery status reports are sent to the
<a href="bounce.8.html"><b>bounce</b>(8)</a>, <a href="defer.8.html"><b>defer</b>(8)</a> or <a href="trace.8.html"><b>trace</b>(8)</a> daemon as appropriate.
<b>SINGLE-RECIPIENT DELIVERY</b>
Some destinations cannot handle more than one recipient per delivery
request. Examples are pagers or fax machines. In addition, multi-
recipient delivery is undesirable when prepending a <b>Delivered-to:</b> or <b>X-</b>
<b>Original-To:</b> message header.
To prevent Postfix from sending multiple recipients per delivery
request, specify
<b><a href="postconf.5.html#transport_destination_recipient_limit"><i>transport</i>_destination_recipient_limit</a> = 1</b>
in the Postfix <a href="postconf.5.html"><b>main.cf</b></a> file, where <i>transport</i> is the name in the first
column of the Postfix <a href="master.5.html"><b>master.cf</b></a> entry for the pipe-based delivery
transport.
<b>COMMAND ATTRIBUTE SYNTAX</b>
The external command attributes are given in the <a href="master.5.html"><b>master.cf</b></a> file at the
end of a service definition. The syntax is as follows:
<b>chroot=</b><i>pathname</i> (optional)
Change the process root directory and working directory to the
named directory. This happens before switching to the privileges
specified with the <b>user</b> attribute, and before executing the
optional <b>directory=</b><i>pathname</i> directive. Delivery is deferred in
case of failure.
This feature is available as of Postfix 2.3.
<b>directory=</b><i>pathname</i> (optional)
Change to the named directory before executing the external com-
mand. The directory must be accessible for the user specified
with the <b>user</b> attribute (see below). The default working direc-
tory is <b>$<a href="postconf.5.html#queue_directory">queue_directory</a></b>. Delivery is deferred in case of fail-
ure.
This feature is available as of Postfix 2.2.
<b>eol=</b><i>string</i> (optional, default: <b>\n</b>)
The output record delimiter. Typically one would use either <b>\r\n</b>
or <b>\n</b>. The usual C-style backslash escape sequences are recog-
nized: <b>\a \b \f \n \r \t \v \</b><i>ddd</i> (up to three octal digits) and
<b>\\</b>.
<b>flags=BDFORXhqu.</b>> (optional)
Optional message processing flags. By default, a message is
copied unchanged.
<b>B</b> Append a blank line at the end of each message. This is
required by some mail user agents that recognize "<b>From</b> "
lines only when preceded by a blank line.
<b>D</b> Prepend a "<b>Delivered-To:</b> <i>recipient</i>" message header with
the envelope recipient address. Note: for this to work,
the <b><a href="postconf.5.html#transport_destination_recipient_limit"><i>transport</i>_destination_recipient_limit</a></b> must be 1 (see
SINGLE-RECIPIENT DELIVERY above for details).
The <b>D</b> flag also enforces loop detection (Postfix 2.5 and
later): if a message already contains a <b>Delivered-To:</b>
header with the same recipient address, then the message
is returned as undeliverable. The address comparison is
case insensitive.
This feature is available as of Postfix 2.0.
<b>F</b> Prepend a "<b>From</b> <i>sender time</i><b>_</b><i>stamp</i>" envelope header to the
message content. This is expected by, for example, <b>UUCP</b>
software.
<b>O</b> Prepend an "<b>X-Original-To:</b> <i>recipient</i>" message header with
the recipient address as given to Postfix. Note: for this
to work, the <b><a href="postconf.5.html#transport_destination_recipient_limit"><i>transport</i>_destination_recipient_limit</a></b> must
be 1 (see SINGLE-RECIPIENT DELIVERY above for details).
This feature is available as of Postfix 2.0.
<b>R</b> Prepend a <b>Return-Path:</b> message header with the envelope
sender address.
<b>X</b> Indicate that the external command performs final deliv-
ery. This flag affects the status reported in "success"
DSN (delivery status notification) messages, and changes
it from "relayed" into "delivered".
This feature is available as of Postfix 2.5.
<b>h</b> Fold the command-line <b>$original_recipient</b> and <b>$recipient</b>
address domain part (text to the right of the right-most
<b>@</b> character) to lower case; fold the entire command-line
<b>$domain</b> and <b>$nexthop</b> host or domain information to lower
case. This is recommended for delivery via <b>UUCP</b>.
<b>q</b> Quote white space and other special characters in the
command-line <b>$sender</b>, <b>$original_recipient</b> and <b>$recipient</b>
address localparts (text to the left of the right-most <b>@</b>
character), according to an 8-bit transparent version of
<a href="http://tools.ietf.org/html/rfc822">RFC 822</a>. This is recommended for delivery via <b>UUCP</b> or
<b>BSMTP</b>.
The result is compatible with the address parsing of com-
mand-line recipients by the Postfix <a href="sendmail.1.html"><b>sendmail</b>(1)</a> mail sub-
mission command.
The <b>q</b> flag affects only entire addresses, not the partial
address information from the <b>$user</b>, <b>$extension</b> or <b>$mail-</b>
<b>box</b> command-line macros.
<b>u</b> Fold the command-line <b>$original_recipient</b> and <b>$recipient</b>
address localpart (text to the left of the right-most <b>@</b>
character) to lower case. This is recommended for deliv-
ery via <b>UUCP</b>.
<b>.</b> Prepend "<b>.</b>" to lines starting with "<b>.</b>". This is needed
by, for example, <b>BSMTP</b> software.
> Prepend ">" to lines starting with "<b>From</b> ". This is
expected by, for example, <b>UUCP</b> software.
<b>null_sender</b>=<i>replacement</i> (default: MAILER-DAEMON)
Replace the null sender address (typically used for delivery
status notifications) with the specified text when expanding the
<b>$sender</b> command-line macro, and when generating a From_ or
Return-Path: message header.
If the null sender replacement text is a non-empty string then
it is affected by the <b>q</b> flag for address quoting in command-line
arguments.
The null sender replacement text may be empty; this form is rec-
ommended for content filters that feed mail back into Postfix.
The empty sender address is not affected by the <b>q</b> flag for
address quoting in command-line arguments.
Caution: a null sender address is easily mis-parsed by naive
software. For example, when the <a href="pipe.8.html"><b>pipe</b>(8)</a> daemon executes a com-
mand such as:
<i>Wrong</i>: command -f$sender -- $recipient
the command will mis-parse the -f option value when the sender
address is a null string. For correct parsing, specify <b>$sender</b>
as an argument by itself:
<i>Right</i>: command -f $sender -- $recipient
This feature is available as of Postfix 2.3.
<b>size</b>=<i>size</i><b>_</b><i>limit</i> (optional)
Don't deliver messages that exceed this size limit (in bytes);
return them to the sender instead.
<b>user</b>=<i>username</i> (required)
<b>user</b>=<i>username</i>:<i>groupname</i>
Execute the external command with the user ID and group ID of
the specified <i>username</i>. The software refuses to execute com-
mands with root privileges, or with the privileges of the mail
system owner. If <i>groupname</i> is specified, the corresponding group
ID is used instead of the group ID of <i>username</i>.
<b>argv</b>=<i>command</i>... (required)
The command to be executed. This must be specified as the last
command attribute. The command is executed directly, i.e. with-
out interpretation of shell meta characters by a shell command
interpreter.
In the command argument vector, the following macros are recog-
nized and replaced with corresponding information from the Post-
fix queue manager delivery request.
In addition to the form ${<i>name</i>}, the forms $<i>name</i> and $(<i>name</i>) are
also recognized. Specify <b>$$</b> where a single <b>$</b> is wanted.
<b>${client_address}</b>
This macro expands to the remote client network address.
This feature is available as of Postfix 2.2.
<b>${client_helo}</b>
This macro expands to the remote client HELO command
parameter.
This feature is available as of Postfix 2.2.
<b>${client_hostname}</b>
This macro expands to the remote client hostname.
This feature is available as of Postfix 2.2.
<b>${client_port}</b>
This macro expands to the remote client TCP port number.
This feature is available as of Postfix 2.5.
<b>${client_protocol}</b>
This macro expands to the remote client protocol.
This feature is available as of Postfix 2.2.
<b>${domain}</b>
This macro expands to the domain portion of the recipient
address. For example, with an address <i>user+foo@domain</i>
the domain is <i>domain</i>.
This information is modified by the <b>h</b> flag for case fold-
ing.
This feature is available as of Postfix 2.5.
<b>${extension}</b>
This macro expands to the extension part of a recipient
address. For example, with an address <i>user+foo@domain</i>
the extension is <i>foo</i>.
A command-line argument that contains <b>${extension}</b>
expands into as many command-line arguments as there are
recipients.
This information is modified by the <b>u</b> flag for case fold-
ing.
<b>${mailbox}</b>
This macro expands to the complete local part of a recip-
ient address. For example, with an address
<i>user+foo@domain</i> the mailbox is <i>user+foo</i>.
A command-line argument that contains <b>${mailbox}</b> expands
to as many command-line arguments as there are recipi-
ents.
This information is modified by the <b>u</b> flag for case fold-
ing.
<b>${nexthop}</b>
This macro expands to the next-hop hostname.
This information is modified by the <b>h</b> flag for case fold-
ing.
<b>${original_recipient}</b>
This macro expands to the complete recipient address
before any address rewriting or aliasing.
A command-line argument that contains <b>${original_recipi-</b>
<b>ent}</b> expands to as many command-line arguments as there
are recipients.
This information is modified by the <b>hqu</b> flags for quoting
and case folding.
This feature is available as of Postfix 2.5.
<b>${queue_id}</b>
This macro expands to the queue id.
This feature is available as of Postfix 2.11.
<b>${recipient}</b>
This macro expands to the complete recipient address.
A command-line argument that contains <b>${recipient}</b>
expands to as many command-line arguments as there are
recipients.
This information is modified by the <b>hqu</b> flags for quoting
and case folding.
<b>${sasl_method}</b>
This macro expands to the name of the SASL authentication
mechanism in the AUTH command when the Postfix SMTP
server received the message.
This feature is available as of Postfix 2.2.
<b>${sasl_sender}</b>
This macro expands to the SASL sender name (i.e. the
original submitter as per <a href="http://tools.ietf.org/html/rfc4954">RFC 4954</a>) in the MAIL FROM com-
mand when the Postfix SMTP server received the message.
This feature is available as of Postfix 2.2.
<b>${sasl_username}</b>
This macro expands to the SASL user name in the AUTH com-
mand when the Postfix SMTP server received the message.
This feature is available as of Postfix 2.2.
<b>${sender}</b>
This macro expands to the envelope sender address. By
default, the null sender address expands to MAILER-DAE-
MON; this can be changed with the <b>null_sender</b> attribute,
as described above.
This information is modified by the <b>q</b> flag for quoting.
<b>${size}</b>
This macro expands to Postfix's idea of the message size,
which is an approximation of the size of the message as
delivered.
<b>${user}</b>
This macro expands to the username part of a recipient
address. For example, with an address <i>user+foo@domain</i>
the username part is <i>user</i>.
A command-line argument that contains <b>${user}</b> expands
into as many command-line arguments as there are recipi-
ents.
This information is modified by the <b>u</b> flag for case fold-
ing.
<b>STANDARDS</b>
<a href="http://tools.ietf.org/html/rfc3463">RFC 3463</a> (Enhanced status codes)
<b>DIAGNOSTICS</b>
Command exit status codes are expected to follow the conventions
defined in <<b>sysexits.h</b>>. Exit status 0 means normal successful comple-
tion.
In the case of a non-zero exit status, a limited amount of command out-
put is reported in an delivery status notification. When the output
begins with a 4.X.X or 5.X.X enhanced status code, the status code
takes precedence over the non-zero exit status (Postfix version 2.3 and
later).
Problems and transactions are logged to <b>syslogd</b>(8). Corrupted message
files are marked so that the queue manager can move them to the <b>corrupt</b>
queue for further inspection.
<b>SECURITY</b>
This program needs a dual personality 1) to access the private Postfix
queue and IPC mechanisms, and 2) to execute external commands as the
specified user. It is therefore security sensitive.
<b>CONFIGURATION PARAMETERS</b>
Changes to <a href="postconf.5.html"><b>main.cf</b></a> are picked up automatically as <a href="pipe.8.html"><b>pipe</b>(8)</a> processes run
for only a limited amount of time. Use the command "<b>postfix reload</b>" to
speed up a change.
The text below provides only a parameter summary. See <a href="postconf.5.html"><b>postconf</b>(5)</a> for
more details including examples.
<b>RESOURCE AND RATE CONTROLS</b>
In the text below, <i>transport</i> is the first field in a <a href="master.5.html"><b>master.cf</b></a> entry.
<b><a href="postconf.5.html#transport_destination_concurrency_limit"><i>transport</i>_destination_concurrency_limit</a> ($<a href="postconf.5.html#default_destination_concurrency_limit">default_destination_concur</a>-</b>
<b><a href="postconf.5.html#default_destination_concurrency_limit">rency_limit</a>)</b>
Limit the number of parallel deliveries to the same destination,
for delivery via the named <i>transport</i>. The limit is enforced by
the Postfix queue manager.
<b><a href="postconf.5.html#transport_destination_recipient_limit"><i>transport</i>_destination_recipient_limit</a> ($<a href="postconf.5.html#default_destination_recipient_limit">default_destination_recipi</a>-</b>
<b><a href="postconf.5.html#default_destination_recipient_limit">ent_limit</a>)</b>
Limit the number of recipients per message delivery, for deliv-
ery via the named <i>transport</i>. The limit is enforced by the Post-
fix queue manager.
<b><a href="postconf.5.html#transport_time_limit"><i>transport</i>_time_limit</a> ($<a href="postconf.5.html#command_time_limit">command_time_limit</a>)</b>
Limit the time for delivery to external command, for delivery
via the named <i>transport</i>. The limit is enforced by the pipe
delivery agent.
Postfix 2.4 and later support a suffix that specifies the time
unit: s (seconds), m (minutes), h (hours), d (days), w (weeks).
The default time unit is seconds.
<b>MISCELLANEOUS CONTROLS</b>
<b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
The default location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
figuration files.
<b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b>
How much time a Postfix daemon process may take to handle a
request before it is terminated by a built-in watchdog timer.
<b><a href="postconf.5.html#delay_logging_resolution_limit">delay_logging_resolution_limit</a> (2)</b>
The maximal number of digits after the decimal point when log-
ging sub-second delay values.
<b><a href="postconf.5.html#export_environment">export_environment</a> (see 'postconf -d' output)</b>
The list of environment variables that a Postfix process will
export to non-Postfix processes.
<b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b>
The time limit for sending or receiving information over an
internal communication channel.
<b><a href="postconf.5.html#mail_owner">mail_owner</a> (postfix)</b>
The UNIX system account that owns the Postfix queue and most
Postfix daemon processes.
<b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b>
The maximum amount of time that an idle Postfix daemon process
waits for an incoming connection before terminating voluntarily.
<b><a href="postconf.5.html#max_use">max_use</a> (100)</b>
The maximal number of incoming connections that a Postfix daemon
process will service before terminating voluntarily.
<b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b>
The process ID of a Postfix command or daemon process.
<b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b>
The process name of a Postfix command or daemon process.
<b><a href="postconf.5.html#queue_directory">queue_directory</a> (see 'postconf -d' output)</b>
The location of the Postfix top-level queue directory.
<b><a href="postconf.5.html#recipient_delimiter">recipient_delimiter</a> (empty)</b>
The set of characters that can separate a user name from its
extension (example: user+foo), or a .forward file name from its
extension (example: .forward+foo).
<b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b>
The syslog facility of Postfix logging.
<b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b>
The mail system name that is prepended to the process name in
syslog records, so that "smtpd" becomes, for example, "post-
fix/smtpd".
<b>SEE ALSO</b>
<a href="qmgr.8.html">qmgr(8)</a>, queue manager
<a href="bounce.8.html">bounce(8)</a>, delivery status reports
<a href="postconf.5.html">postconf(5)</a>, configuration parameters
<a href="master.5.html">master(5)</a>, generic daemon options
<a href="master.8.html">master(8)</a>, process manager
syslogd(8), system logging
<b>LICENSE</b>
The Secure Mailer license must be distributed with this software.
<b>AUTHOR(S)</b>
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA
PIPE(8)
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